1. Field of Invention
The present invention relates to refrigeration appliances and more particularly to a refrigeration system for cooling multiple compartments.
2. Description of Related Art
In typical domestic refrigeration appliances, the appliance frequently has two separate compartments that are maintained at different temperatures. For example, there may be a freezer compartment which has a temperature maintained below 0.degree. C. and a fresh food compartment which is maintained at a temperature somewhat above 0.degree. C. In most commercially available refrigerators, the two different temperature compartments are cooled by single evaporator located in the freezer compartment.
In many instances, however, it may be desirable to provide a refrigeration appliance having three or more compartments in a stacked arrangement. This is often accomplished by providing two main compartments, one below 0.degree. C. and one above 0.degree. C., and partitioning one of the compartments into additional compartments--with minimal temperature variations between the partitioned compartments. In this manner, while three or more compartments are provided, often with separate access doors, only two substantive temperature zones actually exist.
An example of this type of refrigerator is shown in U.S. Pat. No. 4,788,832, which discloses a refrigerator having an upper freezer compartment and a lower refrigerator compartment. The lower refrigerator compartment is divided into two compartments--a middle fresh food type compartment and a bottom drawer-type fresh food compartment. While small temperature differences may exist between the middle and bottom compartment, since these compartments are not separated by insulation these temperature differences are minimal. This type of configuration provides three access doors but only two substantive temperature zones exist within the refrigerator.
Another example is U.S. Pat. No. 5,056,332, which discloses a refrigerator having an upper freezer compartment and a lower refrigeration compartment. The lower refrigeration compartment is further partitioned into an ice temperature compartment and a vegetable compartment. Separate baffles control cold air flow through independent passages to the lower refrigeration compartment and the ice temperature compartment such that the compartments may be maintained at respective predetermined temperatures in a temperature range of -1.degree. C. to -3.degree. C. The upper freezer and lower refrigeration compartments each have hinged doors and the ice temperature compartment and vegetable compartment are configured as slidable drawers.
U.S. Pat. No. 3,075,366 discloses a refrigerator having a main upper food storage compartment and a lower freezer compartment. The upper food storage compartment includes a horizontal partition for separating a drawer-type compartment from the main upper food compartment.
Other refrigerators provide three or more compartments wherein each compartment is thermally insulated from the other compartments and substantive differences in the temperature between compartments may exist. U.S. Pat. No. 5,377,498 discloses a refrigerator having three compartments--a top freezer compartment at approximately -18.degree. C., a middle freezing compartment at approximately 0.degree. C., and a bottom fresh food compartment at approximately 5.degree. C. A plurality of dampers control air flow through a plurality of conduits such that each compartment can be independently supplied with cold air from an evaporator. The evaporator is disposed in either the bottom fresh food compartment or the upper freezer compartment and may be potentially operated at a plurality of different pressures.